As a candidate of the standard of post-quantum cryptography for NIST, Liu, et al. submitted a new public-key encryption scheme Compact-LWE, whose structure is similar to LWE, but with different distribution of errors. They thought that the special error distribution would protect Compact-LWE from known lattice-based attacks. Furthermore, they recommended a set of small parameters to improve the efficiency of Compact-LWE and claimed it can offer 192-bit security. However, in this paper, the authors show that Compact-LWE is not secure under recommended parameters by presenting two ciphertext-only attacks. First, the authors show that the message can be recovered efficiently from the ciphertext. Then the authors go further to recover an equivalent private key efficiently from the public key by exploiting the special structure of Compact-LWE.
Direct reduction is an emerging technology for the utilization of refractory iron ore. With this technology, iron oxides in the ore can be reduced to recoverable elemental iron. The structure of granular aggregates in direct reduction products was investigated by X-ray diffraction (XRD). The results show that iron is mainly generated as a shell in the outer edge of the aggregates. The thermal conductivity of the iron shell is higher than that of other minerals. Thus, minerals close to the iron shell cool faster than those in the inner shells and do not crystallize well. These minerals mainly become stage 2 tailings. Hence the XRD intensity of stage 2 tailings is lower than that of stage 1 tailings. When iron is mainly generated in the interior of the aggregates, the crystallinity of stage 2 tailings will be higher than that of stage 1 tailings. This indicates that the crystallinity of tailings can be used as a marker for the aggregate structure. 相似文献